[crac] RFR: 8350845: [CRaC] Support C/R engines in form of a library [v2]

[Timofei Pushkin]

On Tue, 4 Mar 2025 12:46:56 GMT, Radim Vansa <rvansa at openjdk.org> wrote:

>> Timofei Pushkin has updated the pull request incrementally with five additional commits since the last revision:
>> 
>>  - Fix platform-specific issues
>>  - Rewrite crexec on C++
>>  - Change engine options help
>>  - Move engine wrapper into its own files
>>  - Address review comments
>
> src/hotspot/share/runtime/crac.cpp line 310:
> 
>> 308:   const char *description = engine.description();
>> 309:   if (description == nullptr) {
>> 310:     log_error(crac)("CRaC engine failed to provide its textual description");
> 
> API says that returning `nullptr` is a valid behaviour - shouldn't log error (maybe just print some placeholder text). The same below.

What I meant is: the API doc says "Returns ... null on error" => if `description == nullptr` then there has been an error in the engine (e.g. it decided to malloc the string and failed) => log the error and exit.

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PR Review Comment: https://git.openjdk.org/crac/pull/207#discussion_r1979490786